Chapter 3

Question 1

Allele

Answer 1

A variant form of a gene at a particular locus on a chromosome.

Example: The gene for eye color has alleles for blue, brown, and green.

Question 2

Epigenetic

Answer 2

Changes in gene expression caused by mechanisms other than changes in the DNA sequence.

Example: Environmental factors can influence epigenetic changes.

Question 3

Gene

Answer 3

A unit of heredity made up of DNA that carries instructions for the development and functioning of an organism.

Example: Genes determine traits like hair color and height.

Question 4

Gene (DNA) Methylation

Answer 4

The addition of a methyl group to DNA, often affecting gene expression without altering the DNA sequence.

Example: Methylation can regulate gene activity.

Question 5

Heterozygous

Answer 5

Having two different alleles of a gene.

Example: If one allele codes for blue eyes and the other for brown eyes, the individual is heterozygous for eye color.

Question 6

Homozygous

Answer 6

Having two identical alleles of a gene.

Example: Homozygous individuals for a recessive gene will express that trait.

Question 7

Mutation

Answer 7

A change in the DNA sequence that can lead to variations in gene function or expression.

Example: Mutations can be caused by errors in DNA replication.

Question 8

Transgenic Animal

Answer 8

An animal that has had a foreign gene deliberately inserted into its genome.

Example: Transgenic mice are often used in research to study specific genes.

Question 9

Wild Type

Answer 9

The typical form of a species as it occurs in nature.

Example: Wild type fruit flies have red eyes.

Question 10

Astrocyte

Answer 10

A type of glial cell that supports neurons, regulates the blood-brain barrier, and maintains the extracellular ion balance.

Example: Astrocytes play a crucial role in brain homeostasis.

Question 11

Axon

Answer 11

The long, slender projection of a neuron that conducts electrical impulses away from the cell body.

Example: Axons can be several feet long in some neurons.

Question 12

Axon Collateral

Answer 12

A branch of an axon that allows a neuron to send signals to more than one target.

Example: Axon collaterals enable complex neural signaling pathways.

Question 13

Axon Hillock

Answer 13

The area of the neuron where the axon originates and where action potentials are initiated.

Example: The axon hillock is critical for integrating signals and initiating nerve impulses.

Question 14

Bipolar Neuron

Answer 14

A type of neuron with two extensions, one axon and one dendrite, often involved in sensory pathways.

Example: Bipolar neurons are found in the retina of the eye.

Question 15

Cell Body (Soma)

Answer 15

The central part of a neuron containing the nucleus and most of the organelles.

Example: The cell body processes incoming signals and generates outgoing signals.

Question 16

Dendrite

Answer 16

Branch-like extensions of a neuron that receive signals from other neurons.

Example: Dendrites are covered in synapses to receive neurotransmitter signals.

Question 17

Dendritic Spine

Answer 17

Small protrusions on dendrites where synapses with other neurons are formed.

Example: Dendritic spines are dynamic structures that can change in response to synaptic activity.

Question 18

Interneuron

Answer 18

A neuron that connects other neurons within the central nervous system.

Example: Interneurons play a crucial role in processing information within the brain.

Question 19

Motor Neuron

Answer 19

A neuron that transmits signals from the central nervous system to muscles or glands.

Example: Motor neurons control muscle contractions and movement.

Question 20

Myelin

Answer 20

A fatty substance that surrounds and insulates axons, speeding up the transmission of electrical signals.

Example: Myelin is essential for efficient nerve conduction.

Question 21

Oligodendroglia

Answer 21

A type of glial cell in the central nervous system that produces myelin.

Example: Oligodendrocytes wrap around axons to form myelin sheaths.

Question 22

Purkinje Cell

Answer 22

A type of large neuron found in the cerebellum with extensive dendritic trees, involved in motor control.

Example: Purkinje cells are crucial for coordinating movement and balance.

Question 23

Pyramidal Cell

Answer 23

A type of excitatory neuron found in the cerebral cortex, characterized by a pyramid-shaped cell body.

Example: Pyramidal cells are key players in cortical information processing.

Question 24

Schwann Cell

Answer 24

A type of glial cell in the peripheral nervous system that produces myelin.

Example: Schwann cells wrap around peripheral nerve axons to form myelin sheaths.

Question 25

Sensory Neuron

Answer 25

A neuron that carries sensory information from the body to the central nervous system. ## Footnote Example: Sensory neurons transmit signals about touch, temperature, and pain.

Question 26

Somatosensory Neuron

Answer 26

A sensory neuron that conveys information about touch, temperature, and pain from the skin and muscles. ## Footnote Example: Somatosensory neurons play a role in perceiving the environment.

Question 27

Blood-Brain Barrier

Answer 27

A selective barrier formed by endothelial cells that protects the brain from harmful substances in the blood. ## Footnote Example: The blood-brain barrier prevents toxins from entering the brain.

Question 28

Channel

Answer 28

A protein structure in the cell membrane that allows specific ions to pass through, facilitating electrical signaling. ## Footnote Example: Ion channels are essential for nerve cell communication.

Question 29

Efferent

Answer 29

Nerve fibers that carry motor commands from the central nervous system to muscles and glands. ## Footnote Example: Efferent neurons control muscle contractions.

Question 30

Excitation

Answer 30

The process by which a nerve or muscle cell becomes activated, usually by an increase in electrical activity. ## Footnote Example: Excitation leads to the generation of action potentials.

Question 31

Gate

Answer 31

A mechanism in ion channels that opens or closes to regulate ion flow. ## Footnote Example: Ion channel gates control the flow of ions in response to signals.

Question 32

Glial Cell

Answer 32

Non-neuronal cells in the nervous system that support, protect, and nourish neurons. ## Footnote Example: Glial cells play a role in maintaining the health of neurons.

Question 33

Microglia

Answer 33

A type of glial cell that acts as the main form of immune defense in the central nervous system. ## Footnote Example: Microglia are involved in immune responses in the brain.

Question 34

Neural Network

Answer 34

A network of interconnected neurons that process specific kinds of information. ## Footnote Example: Neural networks are the basis of brain function and information processing.

Question 35

Neuroplasticity

Answer 35

The ability of the brain to change and adapt in response to experience, injury, or learning. ## Footnote Example: Neuroplasticity allows the brain to rewire and recover from damage.

Question 36

Nuclei (sing. Nucleus)

Answer 36

Clusters of neuron cell bodies in the central nervous system. ## Footnote Example: Nuclei in the brain are involved in specific functions like motor control.

Question 37

Pump

Answer 37

A protein that actively transports ions or molecules across a cell membrane against their concentration gradient. ## Footnote Example: Sodium-potassium pumps maintain the cell's resting membrane potential.

Question 38

Synapse

Answer 38

The junction between two neurons where communication occurs through neurotransmitter release. ## Footnote Example: Synaptic transmission is essential for neural signaling.

Question 39

Terminal Button (End Foot)

Answer 39

The end of an axon where neurotransmitters are released into the synapse. ## Footnote Example: Terminal buttons contain vesicles filled with neurotransmitters.

Question 40

Down Syndrome

Answer 40

A genetic disorder caused by the presence of an extra chromosome 21, characterized by developmental delays and physical abnormalities. ## Footnote Example: Down syndrome is the most common chromosomal disorder.

Question 41

Dystonia

Answer 41

A movement disorder causing involuntary muscle contractions, resulting in repetitive movements or abnormal postures. ## Footnote Example: Dystonia can affect one or multiple body parts.

Question 42

Ependymal Cell

Answer 42

A type of glial cell that lines the ventricles of the brain and the central canal of the spinal cord, involved in the production of cerebrospinal fluid. ## Footnote Example: Ependymal cells help circulate cerebrospinal fluid in the brain.

Question 43

Huntington Disease

Answer 43

A genetic disorder causing the progressive breakdown of nerve cells in the brain, leading to motor, cognitive, and psychiatric symptoms. ## Footnote Example: Huntington disease is inherited in an autosomal dominant pattern.

Question 44

Hydrocephalus

Answer 44

A condition characterized by the accumulation of cerebrospinal fluid within the ventricles of the brain, causing increased pressure. ## Footnote Example: Hydrocephalus can lead to brain damage if not treated.

Question 45

Paralysis

Answer 45

The loss of the ability to move or feel sensations in part of the body, typically due to nerve damage. ## Footnote Example: Paralysis can result from spinal cord injuries.

Question 46

Tay-Sachs Disease

Answer 46

A genetic disorder resulting in the destruction of nerve cells in the brain and spinal cord. ## Footnote Example: Tay-Sachs disease is more common in certain ethnic groups.

Question 47

Huntington Disease

Answer 47

A genetic disorder causing the progressive breakdown of nerve cells in the brain, leading to motor, cognitive, and psychiatric symptoms. ## Footnote Example sentence: Huntington Disease is characterized by involuntary movements and cognitive decline.

Question 48

Hydrocephalus

Answer 48

A condition characterized by the accumulation of cerebrospinal fluid within the ventricles of the brain, causing increased pressure. ## Footnote Example sentence: Hydrocephalus may require surgical intervention to relieve the pressure.

Question 49

Paralysis

Answer 49

The loss of the ability to move or feel sensations in part of the body, typically due to nerve damage. ## Footnote Example sentence: Paralysis can result from a spinal cord injury.

Question 50

Tay-Sachs Disease

Answer 50

A genetic disorder resulting in the destruction of nerve cells in the brain and spinal cord, leading to severe neurological symptoms and early death. ## Footnote Example sentence: Tay-Sachs Disease is more common in certain ethnic populations.

Question 51

Tumor

Answer 51

An abnormal mass of tissue resulting from uncontrolled cell growth, which can be benign or malignant. ## Footnote Example sentence: A biopsy is often necessary to determine if a tumor is cancerous.

Question 52

Phenotypic Plasticity

Answer 52

The ability of an organism to change its phenotype in response to environmental influences. ## Footnote Example sentence: Phenotypic plasticity allows plants to adapt to different climates.

Question 53

Protein

Answer 53

A molecule composed of amino acids that performs various functions in the body, including structural, enzymatic, and regulatory roles. ## Footnote Example sentence: Proteins are essential for muscle growth and repair.

Question 54

Wild Type

Answer 54

The typical form of a species as it occurs in nature. ## Footnote Example sentence: Genetic mutations can alter the wild type phenotype.